1. Field of the Invention
The invention relates to a mounting element for a flat insulating body which can be mounted on a thin-walled base, particulary on the sheet metal of a duct of an air-conditioning system, particularly a heat-insulating mat or board, comprising a pin the one end of which is constructed for perforation of the insulating material and the other end of which is provided with a means for attachment to the base, and a clamping plate, which can be clamped to the pin, for holding the insulating body which can be pushed onto the pin.
A main field of application of such mounting elements is the attachment of insulations of ducts in an air-conditioning system. Such ducts are produced from thin-walled metal sheets, particularly galvanized steel sheets which can be easily bent. Because of the media carried in the ducts for the purpose of the air-conditioning, particularly conditioned air, it is necessary for the purpose of blocking heat and noise to line the ducts, which are frequently run in a complicated manner, with insulation. The insulation used is for example fibreglass mats which carry aluminium foil lining on one side. After such mats are attached to the ducts by means of the mounting elements, the aluminium foil lining is on the outside.
The insulation of such and similar thin-walled bases must be durable which makes special demands among others, on the firm seating of the insulating material on the base. As a rule, this can only be achieved by a double positive connection which on the one hand, holds the insulating material on the base, and on the other hand, joins the base to the insulating material. Such a closing shape requires multiple perforation of the thin-walled base and of the insulating material. Perforating the base already presents problems for reasons of its thin walls because, among other things, the buckling strength is relatively low and because, particularly in the case of the air-conditioning ducts, corrosion protection, for example galvanizing is present, the effects of which must not be impaired. The perforations of the insulating material can be generally easily effected as such because of its loose mass but they must make it possible that the insulation rests over its full area on the base in order to avoid areas which are not insulated. These conditions are best met by pointed thin steel pins which can penetrate the insulating material with corresponding ease and can be joined form closed to the material via clamping plates which are clamped to a roughened part-section of the pin behind the point of the pin.
2. Discussion of Prior Art
It is known to provide the pins with an adhesive head because of the abovementioned conditions set by the thin-walled base. In this case, the perforating of the thin-walled base and the associated damage to any galvanizing is eliminated, but with it the positive connection to the base. The non-positive connection which can be achieved by bonding is not always adequate. But bonding has the disadvantage, which it has hitherto not been possible to eliminate, that it is not durable enough to achive the life of air-conditioning systems with the available adhesives. Although this does not make such an ambodiment immediately unusable, it pre-supposes continuous monitoring and repair work which is costly and impractical.
In addition, it is known from DE-A 3,106,844 to attach insulating material to a roof cover base of metal by means of a threaded screw which, by means of its screw head, holds on the side of the insulating material facing away from the base a large-area washer which, in turn, holds the insulating material. The point of the screw shaft is constructed as a drill tip and the thread as a self-cutting thread. Attaching the insulating material to the roof cover base by means of such a screw is expensive because the screw must be screwed into the base if the insulating material rests against the base. This type of assembly of large-area insulating plates is possible only if either the insulating plates are resting on the roof and thus are self-supporting or are held by temporary holding means. In addition, it is necessary with this type of attachment of insulating material that the screws have a relatively large shaft cross-section and have the same cross-section even in the threadless shaft as in the area of the self-cutting thread so that the free length of the shaft can be passed through the insulating material. Without such passage and without a relatively large cross-section it is hardly possible, when applying force to the remote screw head, to set the screws accurately and to transfer the required torque without kinking or bending of the shaft to the drill tip and to the thread.